Toner reclaiming method

ABSTRACT

A toner reclaiming method includes the steps of directing removed toner particles into the vicinity of a surface and electrically charging the particles to a potential that will attract them to the surface, and then removing the toner particles from the surface and combining them with a flow of carrier beads so that a developing mixture is collected for reuse.

United States Patent [191 Donohue et a1.

1 TONER RECLAIMING METHOD [75] Inventors: James M. Donohue, Rochester;

Dennis P. Gerbasi, West Webster, both of NY.

[73] Assignee: Xerox Corporation, Rochester, NY.

[22] Filed: Aug. 2, 1971 [21] Appl. No.: 168,378

Related US. Application Data 7 [62] Division of Scr. No. 847,866, Aug.6, 1969, Pat. No.

[52] U.S. C1 117/19, ll7/17.5, 117/102 A, 355/15 [51] Int. Cl.. 603g13/08, 003g 13/22, B44d U094 [58] Field of Search 118/637; 355/15;1l7/l7.5, 117/102 A, 19; 317/3 [56] References Cited UNITED STATESPATENTS 2,732,775 1/1956 Young et a1. 117/17.5 2,820,716 1/1958 Harmonct a1... 117/l7.5 2,920,987 l/1960 Landry et a1. 117/102 R 6/1960Crumrine l17/17.5

ELECTRICAL POTENTIAL 7 SOURCE 5] June 11, 1974 Primary ExaminerWilliamD. Martin Assistant Examiner-M. Sofocleous [5 7] ABSTRACT A tonerreclaiming method includes the steps of directing removed tonerparticles into the vicinity of a surface and electrically charging theparticles to a potential that will attract them to the surface, and thenremoving the toner particles from the surface and combining them with aflow of carrier beads so that a developing mixture is collected forreuse.

2 Claims, 3 Drawing Figures PKTENTEDJun 1 1 mm- SHEET 2 OF 2 ELECTRICAL1Q POTENTIAL SOURCE TONER RECLAIMING METHOD This is a division ofapplication Ser. No. 847,866, filed Aug. 6, 1969, and now US. Pat. No.3,654,901.

This invention relates to particle reclaiming systems, and particularlyto a toner reclaiming system that is particularly adapted for use withautomatic copiers/reproducers capable of high speed operation.

As is well known in recent years, the steadily increasing size ofvarious industries has required an enormous increase in the amount ofpaper work that must be accomplished, maintained and made available forwide interplant circulation. Present day commercial auto maticcopiers/reproduction machines for this purpose are adapted to producecopies of between and 60 sheets of copy per minute and are capable ofeffecting solid area development. Enormous amounts of developingmaterial are consumed during long run productions and to a large extenta relatively large amount of some of this material is lost or diverted,requiring frequent additions of the material to the development systemfor the machines. Heretofore, there has been no effective way in whichto recover residual toner collected or otherwise made available from adeveloping system and which will insure the opportunity to recover thetoner particles for latter use.

It is, therefore, the principal object of this invention to improveelectrostatic reproduction machines by returning most of the residualdeveloping material cleaned from an electrostatic insulating plate tothe developing system for reuse upon the plate.

Another object of this invention is to reclaim toner particlespreviously removed from an insulating plate automatically and to conveythe toner particles with supporting carrier particles back into thedeveloping system.

These and other objects of this invention are obtained by means of anelectrically biased rotating drum arranged in the path of movement of anair flow containing toner previously cleaned from a photoconductor plateand directing carrier beads upon the drum to clean off and permit thereturn of the toner particles back into a developing system.

For a better understanding of the invention as well as other objects andfurther features thereof, reference is had to the following detaileddescription of the invention to be read in conjunction with theaccompanying drawings wherein:

FIG. 1 is a schematic sectional view of a reproduction machineincorporating the present invention therein with the processingcomponents in section to better illustrate the environment for thepresent invention;

FIG. 2 is a toner cleaning mechanism for the reproduction machine; and

FIG. 3 is a schematic view, partly broken away, of a reclaiming systemused in conjunction with the cleaning mechanism for the reproductionmachine.

For a general understanding of the illustrated copier/reproductionmachine, in which the invention may be incorporated, reference is had toFIGS. 1 and 2 in which the various system components for the machine areschematically illustrated. As in all electrostatic systems such asxerographic machine of the type illustrated, a light image of a documentto be reproduced is projected onto the sensitized surface of axerographic plate to form an electrostatic latent image thereon.Thereafter, the latent image is developed at a working zone with anoppositely charged developing material comprising carrier beads andsmaller toner particles triboelectrically adhering thereto to form axerographic powder image, corresponding to the latent image on the platesurface. The powder image is then electrostatically transferred to asupport surface to which it may be fixed by a fusing device whereby thepowder image is caused permanently to adhere to the support surface.

The electrostatically attractable developing material commonly used indry electrostatic printing comprises a pigmented resinous powderreferred to here as toner and a carrier of larger granular beads formedwith glass, sand, polymer material or steel cores coated with a materialremoved in the triboelectric series from the toner so that atriboelectric charge is generated between the toner powder and thegranular carrier. The carrier also provides mechanical control so thatthe toner can be readily handled and brought into contact with theexposed xerographic surface. The toner is then attracted to theelectrostatic latent image from the carrier to produce a visable powderimage on an insulating surface while the partially toner-depletedcarrier beads are brought back into the developing system for themachine wherein it is mixed with developing material and a new supply oftoner prior'to reuse.

In the illustrated machine, an original D to be copied is placed upon atransparent support platen P fixedly arranged in an illuminationassembly generally indicated by the reference numeral 10, arranged atthe left end of the machine. While upon the platen, an illuminationsystem flashes light rays upon the original thereby producing image rayscorresponding to the informational areas on the original.

The image rays are projected by means of an optical system to anexposure station A for exposing the photosensitive surface of a movingxerographic plate in the form of a flexible photoconductive belt 12.

The exposure of the belt surface to the light image discharges thephotoconductive layer in the areas struck by light, whereby thereremains on the belt a latent electrostatic image in image configurationcorresponding to the light image projected from the original on thesupporting platen. As the belt surface continues its movement, theelectrostatic image passes through a working zone or developing stationE in which there is positioned a developer assembly generally indicatedby the reference numeral 14 and where the belt is maintained in a flatcondition. The developer assembly 14 comprises horizontally andvertically conveying mechanisms which carry developing material to theupper part of the belt assembly whereat the material is dispensed anddirected to cascade down over the upwardly moving inclined selenium belt12 in order to provide development of the electrostatic image.

As the developing material is cascaded over the xerographic plate, tonerparticles in the development material are deposited on the belt surfaceto form powder images. As toner powder images are formed additionaltoner particles are supplied to the developing material in proportion tothe amount of toner deposited on the belt during xerographic processing.For this purpose, a toner dispenser generally indicated by referencenumeral 15 is used to accurately meter toner to the developer materialin the developer assembly 14.

3, The developed electrostatic image is transported by the belt 12 to atr'ansfer' Station C whereat a sheet of copy paper is moved at a speedin synchronism with the moving beltin order to accomplish transfer ofthe ished copy is discharged from the apparatus at a suit able point forcollection externally of the apparatus.

The next and final station in the device is a belt cleaning stationhaving positioned therein a corona precleaning device 24 similar to acorona charging device to impose an electrostatic charge on the seleniumbelt and residual toner particles adherent thereto to aid in effectingthe removal of the particles and a belt cleaning assembly 25 including arotating brush device adapted to remove any powder remaining on thexerographic belt after transfer. it is believed that the foregoingdescription is sufficient for the purposes of this application to showthe general operation of an electrostatic copier using an illuminationsystem constructed in accordance with the invention. For further detailsconcerning the specific construction of the electrostatic copier,reference is made to copending application Ser. No. 731,934, filed May24, 1968 in the name of Hewes et al., now US. Pat. No. 3,661,452.

The belt cleaning assembly 25 shown in FIG. 2 comprises an elongatedrotatable brush of such construction as to apply extremely lightpressure to the photoconductive surface of the selenium belt 12 and todislodge any powder particles that may adhere thereto. The brush ispreferably formed of synthetic fur secured to a rigid cylinder 31 whichin turn is secured to a shaft 32 of a motor (not shown) mounted in frame33 of the machine. The brush is rotatably supported in an elongatedhousing 34 secured bynuts to a discharge nozzle adaptor 35 which in turnis supported on the machine frame 33.

For containing toner powder particles removed from the belt 12 by thebelt cleaning device, the housing 34 encompasses approximately theentire brush area and when applied to the belt 12 the open end of thehousing is nearly rendered closed by the adjacent surface of the belt.in order to insure as close as possible an air tight relationshipbetween the selenium belt 12 and the interior of the brush housing 34,the upper edge portion of the housing is provided with an adjustableseal plate I tion of the housing 35 is provided with an adjustable sealplate 37 which has a leading edge that may be moved toward and away fromthe belt 12 in order to brush cylinder31 and a length generally equal tothe length of the cylinder.

The adaptor 35, which is in communication with the 1 interior of thehousing 34, serves to connect the housing to an inlet duct of a tonerreclaiming system generally indicated by the reference numeral 40.

The toner reclaiming system comprises a generally cylindrical housing 41having mounted therein for rotation by-suitable bearings a drum 42arranged with its circumferential wall concentric with the outer wall ofthe housing 41. The interior of the housing 41 is connected to theinterior of the brush housing 34 by a duct 43 by way of the adaptor 35.The interior of the housing 41 is also connected by way of a duct 44 toan exhaustblower 45 having its outlet arranged to direct exhaust air outof the machine and into the surrounding atmosphere. A filter 46 is inthe path of movement of this exhaust air in order to insure that onlyfiltered air reaches the atmosphere. In conventional brush cleaningexhaust systems for electrostatic machines, the brush cleaner 25, theducts 43, 44 and the exhaust blower 45 with the filter 46 comprise theusual electrostatic plate cleaning system.

Some of these conventional machines may replace the plane filter 46 witha filter bag adapted to not only insure the atmospheric exhaust of cleanair, but also to accumulate toner particles which then can be removedfrom the filter bag and repackaged for toner supply purposes. In thepresent invention, however, the toner reclaiming system 40 is interposedbetween a brush cleaner and its conventional exhaust system.

The duct 43 serves as the input for the reclaiming system housing 41 andbecause of the blower 45, directs a flow of air therein from theinterior of the brush housing 34. This flow of air conveys and directstoner particles just previously removed from the photoconductive belt 12upon the circumferential surface of the reclaiming drum 42 at an acuteangle relative to a tangent at the point of contact therewith. The airis then directed through an arcuate space 47 defined by the surface ofthe rotating drum and the adjacent section of the housing 41. Withinthis space is insulatingly mounted corona emitting wires 48 electricallyconnected to a source of electric potential.

The potential induced upon the wires 48 is relatively high and the tonerparticles passing through the space 47 become electrically charged dueto the high ionizing field produced by the corona emitting wires. Thecharged toner particles, now ionized, seek the nearest surface ofdifferent potential which will be at the surface of the drum 42,preferably held at ground potential. Air effectively free of tonerleaves the space 47 and enters the duct 44 to be exhausted by the blower45. As the drum 42 continues rotation, it collects and carries the toneradhering to its surface past a baffle structure 50 held close to theperipheral surface of the drum 42 and which separates the exhaust duct44 from a return duct 51. The return duct5l is in communication with anarcuate space 52 separating another portion of the peripheral surface ofthe drum 42 and the interior surface of the adjacent section of housing41. This space 52 is also in communication with a duct 53 which isconnected to a source of carrier beads for the development materialbeing utilized by the electrotion for accepting additional tonerparticles when brought in contact therewith.

As previously stated, the carrier particles are made of material or, arecoated with material occupying a position on the triboelectric scaledifferent than the position of the toner particles so that when thecarrier beads and toner particles are brought into contact, the tonerwill adhere to the carrier beads. The source of carrier beads ispreferably a part of the developing system itself which for the presentillustration will originate from a point wherein the carrier beads arein their most depleted stage.

As shown in FIG. 1, the developing material M is shown as being directedfrom an upper horizontal conveyor dispenser tube 60 and into position tocascade over the upwardly moving run of the photoconductive belt 12. Asthe carrier beads cascade down the inclined slope at the developmentstation B, toner is removed from the beads during the developingprocess. As the remaining development material is directed away from thebelt 12 by means of a chute 61, it is returned back into the developingsystem of the machine by being conveyed into a lower horizontal conveyortube 62. A vertical conveying means (not shown) will carry the remainingdeveloping material along with newly added toner particles upperly fromthe conveyor tube 62 and into the conveyor tube 60 in order to present acontinuous flow of development material during operation of the machine.

For the developing system shown in FIG. 1, the point where carrier beadswhich are in the most depleted condition will be while they are beingremoved from the vicinity of the belt 12 and sliding down the chute 61.The input tube 53 for the carrier beads is connected to an openingformed in the chute in order to receive some of the depleted carrierbeads and to direct the same into the toner reclaiming system 40 byforce of gravity. With the drum 42 moving in a direction indicated bythe arrow, and with the carrier beads being driven against the surfaceat an acute angle relative to the tangent at the point of engagementwith the periphery of the drum, the carrier beads will strike the drumsurface thereby dislodging the adhering toner particles therefrom. Withthe carrier beads in the space 52 and the ducts 51, 53 moving in thedirection indicated by the arrows, the dislodged toner particles areremoved from the space 52. From the space 52, the carrier beads tonerparticle mixture, is directed by the duct 51 and conveyed to theinterior of the lower conveyor tube 62 for the developing system 14. Inthis manner, the car rier beads with their toner particles adheringthereto to form usable developing material are returned to thedeveloping system to be utilized therein for continued development bythe system. A blade 65 is secured to the housing 41 and contacts thesurface of drum 42 at an angle relative to the tangent of the drum atthat point. The blade cleans off the remaining toner particles stilladhering to the drum and is arranged so that the scraped off toner is inthe flow of carrier beads that contact toner particles in the space 52.

While the invention has been described with reference to the structuredisclosed herein, it is not confined to the details set forth; but isintended to cover such modifications, or changes as may come within thescope of the following claims.

What is claimed is:

l. A method for reclaiming residual toner particles from aphotosensitive material in a reproduction machine of the type utilizinga developing system, and a developing mixture comprising carrier beadsand toner particles comprising:

a. removing the residual toner particles from said photosensitivematerial,

b. directing the removed particles to a space adjacent a surface andelectrically charging the removed toner particles to a potential wherebythe toner particles will be attracted to said surface when reaching saidspace, and

c. contacting said surface with carrier beads to remove toner particlesfrom said surface and form a mixture of toner particles and carrierbeads.

2. A method as set forth in claim 1, and including the further step ofremoving any toner particles not removed by the step of contacting saidsurface with said carrier beads.

2. A method as set forth in claim 1, and including the further step ofremoving any toner particles not removed by the step of contacting saidsurface with said carrier beads.